Refining hydrocarbon oil



- May 14, 1946. Y YH. G. ',Sczl-IUTZEy Y 2,400,373

Y Y REFINING HYDRO'CARBON OIL Filed Aug. 2a. 194s Fresh y Sulfuric Acid Y Acid sludge 1 Spenf Fresh Caustic Caustic Spray Nozzles Nifrafon Grade To uene Spent Caustic www A. fArroR/vEY,

Patented May 14, 1,946`

,A l REFINING HYDROCARBON oIL Henry G. Schutze, Goose Creek, Tex., assignor to Standard Oil Development Company, a corpol ration of Delaware 'Applicaties August 28, 41943, serial No'. 500,310

. 3 claims.. (cl. 19e-3s)v This 'inventionpertains to lthe finishing of quantities (1.0% or over) of olenic compounds. This invention is particularly adaptable to the toluene from concentrates containing appreciable sulfonated compoundsmust be either hydrolyzed, removed, or rendered stable to temperatures in excess of 500 F. or they will decompose in the distillation step with the liberation f, free sulfur.

finishing of synthetic toluene produced by the 5v dioxidewhich will be contained in the finished catalytic dehydrogenation of` methylcyclohexane and related compounds since by this process undesirable by-products arev formed, consisting iny the main of olenic compounds, which render the concentration and finishing. of the toluene a difiicult operation. Th'e ymethod herein described presents one method by which these diillculties can' be overcome and by which toluene of satisfactory stability with respect to acid wash color is producible. i e

A synthetic toluene .mixture resulting from a catalytic dehydrogenation process may be vconcentrated as a 200' F. to 250 F. boiling range fraction by distillation and then subjected to liquid sulfur dioxide extraction wherein an. extract is produced containing approximately 80% toluene, from to 19% of high boiling parafnic and aromatic compounds and from 1 to 5% olefinic compounds. f

It has now been discovered that a hydrocarbon fraction of the character above described may be treated to obtain a nitrationgrade toluene ofv improved stability by a process including the following steps. The temperature of the extract from the sulfur dioxide extraction process is` adjusted to approximately 80F. and the extract is then acid treated in a two stagev acid treater.

Fresh acid is employedin the second stage and acid sludge withdrawn from the second stage is utilized to pretreat the extract in the .first stage. Subsequent to the acid treatment 'caustic soda solution of from 18 to 20 B. is employed to' neutralize'the acid oil. 'I'he neutralized acid oil is then hydrolyzed at a temperature in the range of 300 to 325 F. in the presence of 18 to 24"y B. caustic soda solution and then separated from the caustic soda solution by settling. 'Ihe hydro-L carbon material withdrawn from ythe settling stage is subsequently distilled and a nltration grade toluene removed asa condensate fraction.

The operation ofthe hydrolyzingstep in the above toluene finishing procedure is of prime importance. Two different types of sulfonated ma`- terialy are contained in the finished n extract charged to this unit. These are the alkyl sulfates 4 months..y $0

which are easily hydrolyzed in the presence of i which are extremely diflicult to hydrolyze vbyl ,steam ork hot causticand the toluene sulfonates The acid wash color instability of toluene containing a trace of sulfur dioxide is exemplified in the following storage data on SO2 contaminated and SO2 free samples -of plant-finished toluene.

finished toluene (acid wash color specification for ,nitratxon grade Storage period toluene is 2 max.)

Somm' SO: Ime

In order to explain the present invention more fully, the preferred treating procedure will be described in conjunction with the drawing in which the single sheet is in the form of a diagrammatic iiow sheet. A toluene containing mixture such as isV obtained yfrom a' sulfur dioxide extraction plantis passed through line I I to incorporator I2,

acid sludge being introduced into the liquid stream flowing through line Il by means of line I3. An.

admixture of acid sludge and thetoluene containing stock is withdrawn from incorporator I2 by une u .end passed into settling vessel l5, n acid sludge layer is withdrawn fromy vessel I5 by line II and a hydrocarbon fraction is withdrawnby line I1, admixed with fresh 'acid from line I8 and passed into incorporator I9 where thorough admixture of thek fresh acid with the hydrocarbon fraction results. From incorporator I9 the mixture passes through line 20 to a secondsettling vessel 2l. Acid sludge from the lower portion of vessel2l isrecycled through line I3 containing pump 22 and the hydrocarbon fraction is withdrawn by line 23, has caustic solution added theresteam or hot caustic. However, both types of to by line 24 and passes into incorporator 25. A

Acidfwavsb color of mixture o caustic and hydrocarbons is withdrawn from the incorporator 25 by line 26 and passes into settling vessel 21. Caustic from the lower fortiori of vessel 21 is withdrawn through line 24 and is recycled by means of pump 28. 1f desired,

' spent caustic may be withdrawn from the recirculating line by outlet 29 and fresh caustic may be added to the recirculating line by inlet 30.

The hydrocarbon fraction from vessel 21. may be withdrawn through line 3i to intermediate storage vessel 32. Hydrocarbon from vessel 32 is withdrawn throughline 33, sent through preheater 34 where it is heated to a temperature in the range of 300 to 325 F and then passed by pipe 35 to vessel 36. Vessel 36 is arranged to allow intimatecontacting of immiscible fractions therein and the settling of said fractions and to this end is provided with recirculating line 31 containing pump 38, and heater 38' and discharging into vessel 36 through spray nozzles 39. Recirculating line 31 is additionally provided with outlet 40 and inlet 4| for the rejection of spent caustic and the addition of fresh caustic.

The toluene' containing fraction injected intov vessel 36 by means of line 35 is thoroughly admixed withcaustic soda 'solution having a gravity in the range of 18 to 24 B. and at a temperature in the range of 300 to 325 F. for no less than ten minutes. This admixing step is carried out in the apparatus disclosed by contacting the.

toluene containing fraction iniected into vessel 36 with 18 to 24 B. caustic which is dispersed through spray nozzles 39 at a high velocity. Heater 38 may be used to maintain the temperatureV of the mixture in the drum at the desired operating temperature of 300 tok 325 F. The retention time of the toluene containing fraction inthe mixing section of the drum must be a minimum of ten minutes. After the mixing period the hyl. drocarbon caustic mixture is conducted to the maintained 1n intimate admixture with the caustic soda for a minimum period of ten minutes,t he total time of contacting and settling must not be less than 1 hour at 300 F. or 1/2 hour at 325 F. It is preferable to renew the caustic soda solution in vessel 36 when its total sulfate content has increased to 40,000 parts per million although, if desired, the sulfate content may be allowed to in. crease to 60,000 parts per million before the renewal step. In ordinary operations the caustic must be renewed when from 300 to 500 barrels of toluene extract have been treated per barrel of caustic.

The toluene containing fraction is passed by line 42 into distillation zone 43 where it is separated by distillation. A light overhead fraction is removed from the zone by line 44, a side stream consisting of the desired stabilized toluene fracl hydrogenation will now be given.

distillation towers' with the toluene being recovered as an overhead fraction from the second of the two towers.

A typical example of a treatment of a toluene containing fraction resulting from catalytic de- A fraction having a boiling range of 200 F. to 450 F. and consisting of toluene, 17.5% high boiling paraiiinic and aromatic compounds and 2.5% oleiinic-compounds with a bromine number of 3 was treated with 9 pounds per barrel of 96% sulfurie acid. The acid treated oil was then contacted withV 20 B. caustic soda solution in the "amount of approximately 1.5 pounds of sodium hydroxide per barrel of oil. The hydrocarbon fraction from this preliminary caustic treatment had a bromine number of 0.3 and contained approximately 2.5 pounds of free sodium hydroxide per 1000 barrels yof oil. The toluene containing charge was then heated to a temperature of 325 F., admixed with.1.5 volumes of 20 B. sodium hydroxide solution at 325 F. and kept inl intimate contactrtherewith for ten minutes in the mixing zone of the hydrolyzer drum. The caustic was separated from the mixture in the settling zoneof the hydrolyzer drum and the toluene containing fractionlwas Withdrawn from the hot caustic solution after a total contact and settling time of one-half hour at 325 F. The separated toluene containingY fraction was then charged to a distillation unit and separated by distillation into a. light overhead consisting of 1.5% of the charge with a bromine number of 2.5, a toluene fraction consisting of '19.0% `of the charge with a bromine number of 0.1 and a purity of 99.5%- toluene and a bottoms fraction consisting of 19.5% of the total.

Having fully described thepresent invention, what I desire to claim is:

1. A process of treating a hydrocarbon oil comprising toluene and olens comprising the steps of acid treating said oil, subsequently neutralizing said acidk treated oil with a concentrated aqueous solution of caustic alkali, separating the caustic solution therefrom, heating the oil to a temperature in the range of 300 to 325 F., admixing the hot oil with an aqueous solution of caustic alkali having a gravity in the range of 18 to 24 B., maintaining said oil in intimate contact with said hot solution for no less than ten minutes, subsequently separating said oil from said hot solution, vaporizing said oil at a 'temperature of no greater than 525 F. and condensing a desired fraction.

2. A process for the treatment of a hydrocarbon yoil comprising toluene and olefins including the steps of admi'xing said oil with concentrated sulfuric acid at approximately atmospheric temperature to form an acid sludge and separating the acid sludge therefrom, subsequently admixing said oil with caustic soda solution of 18 to 20 B. `atl approximately atmospheric temperature and separating said oil from said caustic soda solution, heating the oil to a temperature in the range of 300 to 325 F., intimately contacting said oil with caustic soda solution of 18 to 24 B. for no less-than ten minutes and subsequently separating the hot caustic soda solution from the oil with a total contacting and separating time of not lesslthan one hour at 300 F. and subsequently distilling said oil at a temperature no higher than 525 F., removing a low boiling fraction as overhead and a desired toluene containing fraction as a side stream.

3. A process for the treatment of a hydrocaroilv with caustic 'soda solution of 18 to 24 B. for no less than ten minutes afd subsequently separating the hot caustic soda solution from the oil with a total contacting and separating time of not less than one-half hour at 325 F.

- and subsequently distilling said oil at a temperature no higher than 525 vF., removing a low boiling fraction as overhead and a desired toluene containing fraction as a side stream.

HENRY G. SCHUTZE. 

